21395945 has 16 divisors (see below), whose sum is σ = 27381888. Its totient is φ = 15993600.

The previous prime is 21395929. The next prime is 21395947. The reversal of 21395945 is 54959312.

It is not a de Polignac number, because 21395945 - 2⁴ = 21395929 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21395899 and 21395908.

It is not an unprimeable number, because it can be changed into a prime (21395947) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12002 + ... + 13668.

It is an arithmetic number, because the mean of its divisors is an integer number (1711368).

Almost surely, 2^21395945 is an apocalyptic number.

It is an amenable number.

21395945 is a deficient number, since it is larger than the sum of its proper divisors (5985943).

21395945 is a wasteful number, since it uses less digits than its factorization.

21395945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1840.

The product of its digits is 48600, while the sum is 38.

The square root of 21395945 is about 4625.5750993795. The cubic root of 21395945 is about 277.6155728861.

The spelling of 21395945 in words is "twenty-one million, three hundred ninety-five thousand, nine hundred forty-five".